1. Field of the Invention
This invention relates to high purity liquid distribution systems. Particularly, this invention relates to means and methods for continuously monitoring the purity and consistency of the liquid product at selected points in the system of liquid purification or distribution system. Specifically, this invention relates to means for continuously receiving samples of ultra pure deionized water from one or more points in the purification or distribution systems and distributing these samples to a variety of analytical instruments. This invention is directed to the ability to deliver samples of liquid to analytical instruments which are truly representative of the liquid stream and which have not been adulterated by the sampling procedure or process.
Today, many industrial manufacturing processes require the use of ultra high pure waler either as a direct process fluid or as a the major component of a liquid product. This is particularly true of the pharmaceutical, electronic and electrical utilities industries. Purity of water used in the pharmaceutical industry is clearly apparent because of the human involvement in the final product. Greater and greater purity of water in the electronics industry is required due to the continuously greater miniaturization in the manufacture of electronic devices on semiconductor substrates such as single crystal silicon wafers. Impurities on the substrates in the region of the electronic device formation causes defects in the devices formed which may considerably lower the yield of good product from the manufacturing process. These impurities can also affect the long term reliability of the product manufactured. It is readily apparent that as greater and greater miniaturization of the device design occurs, there is a much greater need go insure removal of impurities, particulary impurities of smaller and smaller size, such as bacteria, bacterial fragments, inert debris and other micro-organisms. The utility industries have a continuously increasing need for high purity water products because of safety and economic issues associated with degradation of high pressure steam containment vessels and heat exchangers, and a variety of scaling and metallurgical problems associated with silicates and other metal corrosion problems.
2. Description of the Prior Art
The necessity for very clean water in the pharmaceutical, electronic and utility industries has been realized for a number of years and much effort has been expended to develope technology for the removal of both chemical and particulate impurities within liquid streams. Purification of water typically requires a variety of process steps with a particular type of impurity being eliminated at each step. FIG. 1 shows a typical water purification facility for electronic, pharmaceutical or utility industries. The execution of all of the process steps at their highest efficiency is required to reach the highest level of water purity at the lowest possible cost.
An additional relevant technology which as fairly recently been explored in water purification and use distribution systems is the use of ozone as an oxidant. A paper on this subject entitled "Purification of Deionized water by Oxidation with Ozone" by Carl Nebel and William W. Nezgod was published in the October 1984 issue of Solid State Technology starting on page 185. This article gives a very complete explanation of the unique properties of ozone for water treatment. In another article entitled "Ultraviolet Light Takes on CPI Role" by Robert E. Legan and published in Chemical Engineering, Jan. 25, 1982, the combination of ultraviolet light with ozone to sterilize water is reported. Without being redundant in the teachings of these articles, the reader is invited to review them for additional information and background.
Due to the formerly less stringent requirements for ultra pure water used in industrial processes, water systems in place are not generally designed or operated efficiently enough to heap the complete advantage of existing water purification technology. Significant improvements in the quality of water in systems in place and significant economics of the operations thereof are accordingly highly desired today. Improvements in sensitive and rapid analysis systems such as this invention which can access multiple process steps and distribution networks for ultra pure water and ultra pure water products can significantly improve both water quality and the economics of water purification and use distribution systems.